Wireless Mesh Networks and Cooperative Relaying Technologies

The Wireless Mesh Network (WMN) has become a focus in research of wireless broadband communications . In a switching technologies - based wireless Mesh network, the entire network is regarded as an IP subnet, so it cannot be applied in situations where large coverage is required . The use of cooperative relaying technologies can improve the transmission rate and reliability of wireless link; while the wireless Mesh network, once integrated with cooperative relaying technologies and routing technologies , can improve its spectrum efficiency and cover a wide area . However, there are many problems to be solved with respect to standardization, key technologies research and industrialization. Therefore , the application of cooperative relaying technologies in wireless Mesh networks is still a great challenge .

Scalability Technologies for Wireless Mesh Networks

The continuous increase of data transmission density in wireless mobile communications has posed a challenge to the system performance of Wireless Mesh Networks (WMNs ). There is a rule for wireless Ad hoc networks that the average node capacity decreases while the number of nodes increases , so it is hard to establish a large - scale wireless Mesh network. Network scalability is very important for enhancing the adaptive networking capability of the wireless Mesh network. This article discusses key scalability technologies for Mesh Base Stations (BSs ) and Mesh Mobile Stations (MSs ), such as channel allocation, intelligent routing , multi- antenna , node classification, Quality of Service (QoS) differentiation and cooperative transmission.

Wireless Mesh Network and IEEE 802 Standards

Although the wireless broadband access system is developing rapidly, its development is limited due to some disadvantages , such as small capacity of bandwidth and small coverage . The Wireless Mesh Network (WMN) is one of the important technologies for 'last mile 'broadband wireless access . The WMN can integrate with multiple wireless systems , such as Wireless Local Area Network (WLAN), Wireless Personal Area Network (WPAN), and Wireless Metropolitan Area Network (WMAN), to improve the performance of the wireless network and enlarge the coverage range . With the wide applications of the WMN, the IEEE 802 standard group is devoted to promoting the development of the WMN technology and establishing the related technical standards . At present, WMN standards have appeared in IEEE 802.11s , 802.15, 802.16, and 802.20.

Wireless Cooperative Mesh Network:A New Architecture for Network Convergence

The convergence of heterogeneous wireless networks is a trend in the evolution of wireless networks.A new architecture for network convergence,named Wireless Cooperative Mesh Network,is proposed to solve such emerging problems in convergence as transmission mode selection,load balancing,routing and handover.The new architecture is based on the structure of Wireless Mesh Networks(WMNs),and cooperative communication is also employed to further optimize its structure and upgrade its performance.It can thus obtain advantages of both the Mesh technology(high spectrum efficiency and dynamic self-organization) and cooperative communication(high diversity gain and high energy efficiency).The new architecture serves as an efficient solution for wireless network convergence.

Wireless Mesh Technology and Network

Wireless Mesh Network (WMN) has been actively researched and developed as a new network technology to support broadband high- speed multimedia services . This paper discusses WMN technology and applications , and introduces the basic technologies , typical applications and current development of the WMN. With the future development of wireless distribution technology and network, wireless Mesh technology and network will become the key networking technology and architecture of wireless mobile communications , and will be widely used in various wireless networks with more important roles .

Key Technologies of Wireless Mesh Network

The Wireless Mesh Network (WMN) is a special kind of Ad hoc network with a hierarchical network structure . Its backbone transmission network has such characteristics as multi- hop , topology stability, no electricity supply constraints , convergence of flows . Improving the spatial reuse of spectrum is an effective approach to increase network capacity. The linchpin of this approach is to effectively control the interference range between wireless links . The multi- channel networking technology is one of the key technologies of WMN, and its core is the channel allocation through which the channel utilization can be maximized . The mutual interference between multi- hop wireless links should be considered when choosing the routing metrics in WMN. Through the load - balancing routing method , the network capacity and throughput of nodes can be improved .

Hop distance fairness for wireless mesh network based on queue management

Wireless mesh network （WMN） is a new multi-hop network for broadband accessing to intemet. However, there exists a server unfairness problem based on different hop distances in WMN. To solve this problem, the unfairness issue was analyzed in test-bed experiment and NS2 simulation. A dynamic queue management scheme E-QMMN was proposed, which allocates the queue buffer according to the hop distance of every flow. The experimental results show that the proposed scheme can not only increase the hop distance fairness of the legacy scheme at most 50%, but also reduce the average round trip time at least 29% in congested WMN environments.

AN ADAPTIVE OPPORTUNISTIC RETRANSMISSION CONTROL SCHEME ENVIRONMENT-AWARE-BASED FOR WIRELESS MULTIMEDIA MESH NETWORKS

In this paper, we propose an aware-based adaptive opportunistic retransmission control scheme for wireless multimedia Mesh networks. The proposed scheme provides maximum retransmis-sion count optimization based on environment-aware to improve packet relay probability. The scheme discriminates the types of packet loss in wireless link by means of environment information and selects the retransmission count by taking the IEEE 802.11 wireless channel characteristics into consideration. Furthermore, the maximum retransmission count of MAC is adjusted adaptively. Extensive simulations demonstrate that the proposed scheme significantly reduces packet collision probability and packet loss rate, and thus improves network throughput.

Drone Based Wireless Mesh Network for Disaster/Military Environment

In recent years, researches of disseminating wireless network have been conducted for areas without network infrastructure such as disaster situation or military disputes. However, conventional method was to provide a communication infrastructure by floating large aircraft as UAV or hot-air balloon in the high air. Therefore, it was difficult to utilize previous method because it requires a lot of time and cost. But it is possible to save money and time by using a drone which is already used in many areas as a small UAV. In this paper, we design a drone that can provide wireless infrastructure using high speed Wi-Fi. After reaching the target area, the drone can provide Wi-Fi using wireless mesh network and transmit the situation of local area through attached camera. And the transmitted videos can be monitored in the control center or cell phone through application in real time. The proposed scheme provides wireless communication of up to 160 Mbps in a coverage of about 200 m and video transmission with a coverage of about 120 m, respectively.

The Network coding based on synchronization in wireless mesh networks self- similar traffic

The wireless mesh networks trathc are of selt：snmlarlty and the network pertOrmance is degraded by seltsimillar traffic. Network coding is a new technology which improves network performance. An algorithm is presented that it uses network coding to reduce queue length and delay time when self-similar traffic occurs. Based on synchronization, data packets are classified by destination address and lengths. Simulation results show that with the proposed synchronization techniques, network coding, even in scenarios with burst self-similar traffic, where network coding could not have been deployed so far, increases throughput and lowers packet loss in wireless mesh networks.

LOAD AWARE ADAPTIVE BACKBONE SYNTHESIS IN WIRELESS MESH NETWORKS

Wireless Mesh Networks(WMNs) are envisioned to support the wired backbone with a wireless Backbone Networks(BNet) for providing internet connectivity to large-scale areas.With a wide range of internet-oriented applications with different Quality of Service(QoS) requirement, the large-scale WMNs should have good scalability and large bandwidth.In this paper, a Load Aware Adaptive Backbone Synthesis(LAABS) algorithm is proposed to automatically balance the traffic flow in the WMNs.The BNet will dynamically split into smaller size or merge into bigger one according to statistic load information of Backbone Nodes(BNs).Simulation results show LAABS generates moderate BNet size and converges quickly, thus providing scalable and stable BNet to facilitate traffic flow.

Available capacity and robust wireless mesh connectivity of TDD-based networks

This paper addresses the available capacity and robust connectivity of time division duplex based wireless mesh networks （TDD-based WMNs）. A stochastic model is presented for TDD-based WMNs. Considering the parameters that affect the network performance like ratio of control slots number to data slots number, collision probability, node density and average hopcounts, the availa- ble capacity for each node is inferred. Meanwhile, the order of transmission range for robust connec- tivity of large scale WMNs is derived. With the stochastic model and inferred available capacity per node, the performance of TDD-based WMNs using IEEE 802.16 standard is analyzed under various conditions. Simulation results indicate that the available capacity of IEEE 802.16-based TDD-based WMNs and the theoretical result have the same increasing and decreasing trend as the node density increases. Simulation results also illustrate the optimal value of the ratio of control slots number to data slots number that maximizes the available capacity.

Reliability Strategies for Data Transmission in Wireless Mesh Network

Wireless Mesh Network (WMN) is a new-type wireless network. Its core idea is that any of its wireless equipment can act as both an Access Point (AP) and a router. Each node in the network can send and receive signals as well as directly communicate with one or several peer nodes. One important issue to be considered in wireless Mesh networks is how to secure reliable data transmission in multi-hop links. To solve the problem, the 3GPP system architecture proposes two functionalities: ARQ and HARQ. This paper presents two HARQ schemes, namely hop-by-hop and edge-to-edge, and three ARQ schemes: hop-by-hop, edge-to-edge, and last-hop. Moreover, it proposes three solutions for WMNs from the perspective of protocol stock design: layered cooperative mechanism, relay ARQ mechanism and multi-hop mechanism.

A Review on Wireless Mesh Networks

Wireless mesh networks (WMNs) are new kind of networking technology which facilitate the extension of wireless local area networks into wide areas and have emerged as a key technology for next-generation wireless networking.Due to the advantages of WMNs over other wireless networks,they are now a promising approach for future network access.Typical applications range from home broadband Internet access and community networking to wireless metropolitan area networks.Meanwhile,the considerable efforts in academic range from network architecture,network capacity,layered communication protocols,security,cross-layer design,etc.Still many technical challenges exist in designing affordable,reliable,and sustainable WMNs infrastructures.In order to provide a better understanding of these challenges,this paper presents a detailed investigation of current technologies for WMNs,and it will help to guide and refocus future works in this area.

A Combined Admission and Priority Control Mechanism for Assuring Communication Quality in VANETs integrated with Wireless Mesh Networks

In this paper, we introduce a new combined priority and admission control mechanism applying in the VCN （Vehicular Communication Network） which is designed with an integration of the Vehicular Ad-hoc Networks （VANETs） based on standard IEEE 802.11 p and IEEE 802.11 s WMNs （Wireless Mesh Networks）. Simulation experiments are intensively investigated to evaluate the novel combined priority and admission control mechanism to assure quality of the I2V （Infrastructure to Vehicle） emergency services occurred during the time video flows are being delivered between content servers and cars. The simulation results show effectiveness of proposed priority and admission control schemes in term of the minimized end-to-end delay as well as the increase of throughput and PDR （Packet Delivery Ratio） of the emergency data flow.

Constructing of wireless emergency communication system for underground coal mine based on WMN technology

Based on the Wireless Mesh Network (WMN), a wireless emergency communicationsystem for underground coal mine which was designed to be capable of videosurveillance, voice communication, and environment monitoring at the same time wasproposed.The network architecture of the system was proposed, and its service model,extensible technology, medium access control, routing algorithm, channel allocation andsystem management technologies were analyzed according to the actual rescue requirementsof underground coal mine and the characteristics of underground spatial structureand radio transmissions.The relevant theories and key technologies were extracted,which would provide theoretical support for the system development.

Hierarchical wireless network architecture for factory network

The traditional wired networks in an industrial firm often encounters large difficulties,such as the cable installation,regular maintenance and cable replacement and so on,all these results in high cost.So,in this paper,we propose an IP-based hierarchical wireless network architecture and apply some of the technologies of 6LoWPAN to it.We verify the proposed architecture via real implementation with a wireless backbone,sensor networks and a connection between those networks.And the IP-based hierarchical industrial network is indeed an advanced network for harsh industrial environments.

无线Mesh网中网络编码的研究进展

无线Mesh网络是一种具有广泛应用前景的无线接入系统,网络编码允许网络节点对接收的数据报文进行加工处理,为解决Mesh网网络问题提供了一条新途径。通过对比在单播中网络编码和传统路由的不同,阐述了网络编码基本原理;然后总结了网络编码的发展现状;分析和归纳了网络编码提高无线Mesh吞吐量、可靠性、安全性等性能的应用;最后对网络编码在Mesh网络中的进一步研究方向进行了展望。

多信道无线Mesh网络的多播信道分配算法

无线Mesh网络可用信道和节点接口的缺乏限制了多播树链路的可用带宽,致使网络吞吐量下降。针对该问题,提出支持多播的多信道多接口信道分配算法——LAMCA。该算法能最小化无线Mesh网络的干扰程度,并最大化网络吞吐量。仿真结果表明,与层次信道分配算法LCA相比,该算法在吞吐量性能方面较优。

一种用于多信道无线Mesh网络的信道分配方法

合理地分配信道是提高多信道无线Mesh网络性能的关键。针对动态信道分配策略平均吞吐率较低的不足,采用相对平衡理论,提出了一种基于可通邻居节点可用信道表的信道分配方法,给出了该方法的主要步骤和具体实现过程,并分析了时间复杂度。节点在进行数据发送前,利用可通邻居节点的可用信道集合,建立可通邻居节点可用信道表和信道优先级队列,在此基础上,选取一个最优信道,并使用改进的RTS/CTS协议进行信道协商和数据收发控制。仿真结果表明,提出的方法在平均吞吐率方面提高了5.2%。